Download Autonomic Nervous System

Homeostasis and the Autonomic Nervous System
•
The autonomic nervous system maintains
homeostasis by adapting your body to the external
environment.
•
1.
Composed of two distinct units:
Sympathetic Nervous System
2. Parasympathetic Nervous System
Homeostasis and the Autonomic Nervous System
•
All autonomic nerves are
motor nerves that
regulate organs without
conscious control.
•
Motor nerves lead to
muscles that are
controlled by conscious
control.
The ANS and Visceral Sensory Neurons
Autonomic Nervous System
•
A.K.A.
• Involuntary N.S.
• Visceral motor
•
system
Automatic N.S.
Autonomic and Motor Nervous System
Anatomy of ANS
Division
Location of
Ganglia
Origin of Fibers
Length of Fibers
Sympathetic
Thoracolumbar
region of the spinal
cord
Short preganglionic Close to the
and long
spinal cord
postganglionic
Parasympathetic
Brain and sacral
spinal cord
Long preganglionic
and short
postganglionic
In the visceral
effector organs
Anatomical
Differences
• Issue from different regions
•
of the CNS
Sympathetic
(thoracolumbar division)
• Parasympathetic
(craniosacral division)
Comparison of Somatic and Autonomic Systems
•
Effectors (Targets)
• Somatic = skeletal muscle
• Autonomic = smooth/cardiac muscles, glands and internal organs
•
Efferent pathways
• Somatic = no ganglia; myelinated axon from ventral horn of
spinal cord all the way to effector
•
Autonomic = 2 neuron pathway; first is preganglionic and body
resides in brain/S.C.; 2nd is postganglionic and body resides in
autonomic ganglion
• Pre’s are lightly myelinated; post’s are unmyelinated
• SNS = short pre/long post ganglionic axon
• PsNS = long pre/short post ganglionic axon
Autonomic and Motor Nervous System
Pre-ganglionic
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings
Post-ganglionic
Ganglion
Comparison of Autonomic and Somatic Motor Systems
Comparison of Autonomic and Somatic Motor Systems
Somatic Motor Division
•
One motor neuron extends from the CNS
to the skeletal muscle (direct connection).
•
The axons are well myelinated, and
conduct impulses rapidly.
Autonomic Nervous System
(Visceral Motor Division)
•
Chain of two motor neurons
 PREGANGLIONIC (PRESYNAPTIC)
MOTOR NEURON - before the
synapse or before the ganglion
 POSTGANGLIONIC
(POSTSYNAPTIC) MOTOR NEURON
- after the synapse or after the
ganglion
•
Conduction is slower due to thinly or
unmyelinated axons.
Anatomical Differences Between Sympathetic and
Parasympathetic Divisions
Length of preganglionic fibers:
• Sympathetic: short preganglionic fibers
• Parasympathetic: long preganglionic fibers
Length of postganglionic fibers
• Sympathetic: long postganglionic fibers
• Parasympathetic: short postganglionic fibers
•
Sympathetic fibers connect to the SYMPATHETIC
CHAIN GANGLIA (collections of neuron cell bodies
in the PNS) before they innervate the organs.
Anatomical Differences Between Sympathetic and
Parasympathetic Divisions
The NEUROTRANSMITTERS
released by the different motor
neurons:
•
Both parasympathetic and
sympathetic preganglionic motor
neurons release
ACETYLCHOLINE.
•
Sympathetic postganglionic
motor neurons – most release
NOREPINEPHRINE.
•
Parasympathetic postganglionic
motor neurons – release
ACETYLCHOLINE
Divisions of the Autonomic Nervous System
• Sympathetic and Parasympathetic Divisions
•
Innervate mostly the same structures, but cause opposite effects
• Sympathetic – “fight, flight, or fright”
Activated during exercise, excitement, and emergencies
Increases heart rate, breathing rate, and blood supply to the skeletal
muscles
• Parasympathetic – “rest and digest”
 Concerned with conserving energy
 Activated during rest and sleep
 Decreases heart rate, breathing rate, and blood supply to skeletal muscles
 Increases blood supply to digestive organs
Comparison of somatic and autonomic systems
Comparison of Somatic and Autonomic Systems
•
Somatics: All motor neurons release ACH which is always
stimulatory.
•
Viscerals: ACH & norepinephrine
• All preganglionic fibers release ACH
• All postganglionic PsNS fibers release ACH
• Most postganglionic SNS fibers release norepinephrine
• Can be stimulatory or inhibitory based on receptor types
Comparison of Somatic and Autonomic Systems
Comparison of Somatic and Autonomic Systems
Comparison of Somatic and Autonomic Systems
•
Branching of axons: Sympathetic axons are highly
branched to influence many organs while parasympathetic
axons have few branches so have a localized effect.
Comparison of Somatic and Autonomic Systems
Comparison of Somatic and Autonomic Systems
Terms
•
Synapse:
•
Ganglion (pl. ganglia):
•
Preganglionic neuron: Cell body lies within the CNS
Junction between 2 neurons that communicates the
message from the presynaptic neuron to the postsynaptic neuron.
A cluster of neuronal cell bodies in the PNS
- Its axon, the preganglionic fiber synapses with the 2nd motor neuron,
the ganglionic neuron, in a peripheral autonomic ganglion
•
Postganglionic fiber (axon) of the ganglionic neuron extends to
the visceral organs.
Ganglia
Sensory
Motor
Spinal ganglion
Sympathetic
Parasympathetic
Trigeminal ganglion
Paravertebral ganglia
(Ganglia of sympathetic
trunk)
Ciliary ganglion
Geniculate ganglion
Prevertebral ganglia
(Collateral ganglia =
preaortic ganglia):
Pterygopalatine ganglion
Spiral (cochlear) ganglion
Submandibular ganglion
Vestibular (Scarpa’s) ganglion
Superior (jugular) and inferior
(petrosal) ganglia of IX
Otic ganglion
Superior (rostral) and inferior
(nodose) ganglia of X
Terminal ganglion
Sympathetic Ganglia- Paravertebral Ganglion
• Along the length of the sympathetic trunk
are ganglia known as ganglia of
sympathetic trunk or paravertebral
ganglia.
• The ganglia are distinguished as
cervical, thoracic, lumbar, and
sacral and, except in the neck, they
closely correspond in number to the
vertebrae.
Arrangement
Only the cervical ganglia have specific
names. They are arranged thus:
Cervical ganglia - 3 ganglia
Thoracic ganglia - 12 ganglia
Lumbar ganglia - 4 ganglia
Sacral ganglia - 4 ganglia
Sympathetic Ganglia - Prevertebral Ganglion
• Prevertebral ganglia (or
collateral ganglia, or preaortic
ganglia) are sympathetic ganglia
which lie between the sympathetic
chain and the organ of supply.
Examples
Include
1. Celiac ganglia
2. Aorticorenal ganglion
3. Superior mesenteric ganglia
4. Inferior mesenteric ganglia
Parasympathetic Ganglia
• Parasympathetic ganglia are the
autonomic ganglia of the
parasympathetic nervous system.
• Most are small terminal ganglia or
intramural ganglia, so named because
they lie near or within (respectively)
the organs they innervate.
• The exceptions are the four paired
parasympathetic ganglia of the head
and neck.
Ciliary ganglion (sphincter

pupillae, ciliary muscle)
 Pterygopalatine ganglion
(lacrimal gland, glands of nasal cavity)
 Submandibular ganglion
(submandibular and sublingual glands)
 Otic ganglion (parotid gland)
Sympathetic Trunk (Chain)
• The paravertebral ganglia form the
sympathetic trunk or chain from neck to pelvis.
• Typically 23 ganglia
• C: 3, T: 11, L: 4, S: 4, Co: 1
• Fibers enter chain from ventral root via white
ramus communicantes (myelinated fibers)
• Found only in T1-L2 cord segments.
• Postganglionics exit ganglia via gray ramus
communicantes (unmyelinated)
• Found along entire length of chain allowing
sympathetic output to reach all areas of the
body.
Preganglionic Options Upon Entering Sympathetic Ganglion
• 1. Synapse w/ a ganglionic neuron w/in
the sympathetic chain (same level,
ascend, or descend).
• 2. Pass thru the chain to synapse
w/collateral ganglia
• These form splanchnic nerves to
supply the abdomen & pelvis
• 3. Synapse directly with adrenal medulla
Sympathetic Trunk
• The sympathetic trunks
(sympathetic chain, gangliated
cord) are a paired bundle of
nerve fibers that run from the
base of the skull to the coccyx.
Sympathetic Trunk
Sympathetic Trunk
Preganglionic Options Upon Entering Sympathetic Ganglion
• 1. Synapse w/ a ganglionic neuron w/in the sympathetic chain
(same level, ascend, or descend).
• 2. Pass thru the chain to synapse w/collateral ganglia.
• These form splanchnic nerves to supply the abdomen & pelvis.
• 3. Synapse directly with adrenal medulla
Preganglionic Options Upon Entering Sympathetic Ganglion
Preganglionic Options Upon Entering Sympathetic Ganglion
Preganglionic Options Upon Entering Sympathetic Ganglion
Sympathetic nervous system
•
•
•
•
•
The sympathetic division is the “fight-or-flight” system.
Involves E activities – exercise, excitement, emergency,
and embarrassment.
Non-essential activities are dampened (GI/urinary).
Promotes adjustments during exercise – blood flow to
organs is reduced, flow to muscles is increased.
Its activity is illustrated by a person who is threatened
• Heart rate increases, and breathing is rapid and deep.
• The skin is cold and sweaty, and the pupils dilate.
• Bronchioles dilate…increasing ventilation, delivering more oxygen
•
•
•
to cells.
Constriction of visceral & cutaneous bv’s (blood is shunted to
skeletal mm)
Liver releases more glucose into blood to provide more readily
avail energy.
Targets adipocytes for lipolysis.
The ANS consists of all visceral motor neurons
innervating smooth muscle, cardiac muscle and
glands.
Sympathetic nervous system
• Its activity is illustrated by a person who is threatened
• Heart rate increases, and breathing is rapid and deep.
• The skin is cold and sweaty, and the pupils dilate.
• Bronchioles dilate…increasing ventilation, delivering more oxygen
•
•
•
to cells.
Constriction of visceral & cutaneous bv’s (blood is shunted to
skeletal mm)
Liver releases more glucose into blood to provide more readily
avail energy.
Targets adipocytes for lipolysis.
Sympathetic Pathways to the Head
•
Preganglionic fibers from T1-T4 ascend sympathetic
chain to synapse w/ superior cervical ganglion
• Fibers run w/ several CN’s & first 4 cervical nerves
• Serve skin & blood vessels of head
• Dilate iris of eyes
• Inhibits nasal & salivary glands (dry mouth w/ nervousness)
• Innervates smooth mm to lift upper eyelid
• sup. cervical ganglion also has direct branches to heart
Sympathetic Pathways to the Body
Sympathetic Pathways to the Periphery
Sympathetic Pathways to the Head
Sympathetic Pathways to the Thorax
•
Fibers from T1-T6
•
Synapse in middle & inferior cervical ganglia
• Enter cervical nerves C4-C8 (heart, thyroid, skin)
•
Some fibers synapse at their respective level & the
postganglionic fibers pass directly to the organ served
• Heart, aorta, lungs, eating tube, thyroid, & skin
Sympathetic Pathways to the Thorax
Sympathetic Pathways to the Thorax
Sympathetic Pathways to the Thorax
Pathways with Synapses in Collateral Ganglia
•
These fibers (T5-L2) have been left the sympathetic
chain without synapsing.
•
They form thoracic, lumbar, and sacral splanchnic
nerves.
•
Their ganglia include the celiac, the superior and
inferior mesenterics, and the hypogastric.
Sympathetic Pathways to the Abdomen
•
•
•
Fibers from T5-L2 traveling in the thoracic
splanchnic nerves
Synapse in mainly the celiac & superior
mesenteric ganglia
Serve stomach, intestines (up to distal ½ of
large intestine), liver, spleen, & kidneys
Sympathetic Pathways to the Abdomen
Sympathetic Pathways to the Abdomen
Sympathetic Pathways to the Abdomen
Sympathetic Pathways to the Pelvis
•
Fibers from T10 – L2 descend to the lumbar & sacral
chain ganglia.
•
Some synapse there & most go out lumbar & sacral
splanchnic nerves to the inferior mesenteric & hypogastric
ganglia.
•
Serves distal ½ of lg intestine, urinary bladder, & pelvic
reproductive organs.
Sympathetic Pathways to the Pelvis
Sympathetic Pathways to the Pelvis
Adrenal Medulla
• Embryologically arises from
the same tissue as
sympathetic ganglia.
• Some fibers in the thoracic
splanchnic nerves pass thru
the celiac ganglion w/o
synapsing & terminate in
the hormone producing
medullary cells of the
adrenal gland.
• Secrete epi & norepi into
the blood.
Sympathetic Pathways to the Adrenal Medulla
Sympathetic Pathways to the Adrenal Medulla
Parasympathetic Nervous System
•
•
•
•
•
SLUDD – Salivation, Lacrimation, Urination, Digestion,
Defecation
Most active in non-stressful situations
Concerned with keeping body energy use low
Lenses of eyes accommodated for close vision
Its activity is illustrated in a person who relaxes after a
meal
• Blood pressure, heart rate, and respiratory rates are low
• Gastrointestinal tract activity is high
• The skin is warm and the pupils are constricted
Parasympathetic Division Outflow
Cranial Outflow Cranial Nerve
Ganglion
Effector Organ(s)
Occulomotor (III)
Ciliary
Facial (VII)
Pterygopalatine
Eye (constriction of
pupils & bulging of
lens for close vision)
Submadibular &
sublingual salivary
glands, nasal, and
lacrimal glands
Parotid salivary
glands
Submandibular
Glossopharyngeal Otic
(IX)
Vagus (X)
Sacral Outflow
Located within the
walls of target organs
(Intramural, terminal)
S2-S4 lateral horns Located within the
walls of the target
organs (Intramural)
Heart, lungs, bronchi,
aorta, liver, gall
bladder, stomach,
small intestine.,
proximal ½ of large
intestine
Large intestine,
urinary bladder,
ureters, and
reproductive organs
Parasympathetic nervous system
• Fibers emergency from
•
C.N.’s III,VII,IX, & X
(>75% of all preganglionic
PsNS fibers) as well as
S2-S4
• AKA craniosacral
division
Long preganglionic fibers
synapse in terminal or
intramural ganglia (w/in
wall of effector)
Parasympathetic Nervous System “cranio-sacral”
• Parasympathetic nerves orjinal from cranial
nerves III, VII, IX, and X and the sacral spinal
cord.
• Occulomotor nerve: fibers to the pupillary
sphincters and ciliary muscle
• Facial nerve: fibers to lacrimal and
submandibular gland
• Glossopharyngeal nerve: fibers to parotid
gland
• Vagus nerve: motor inputs to visceral
organs sacral segments - fibers to descending
colon, rectum, bladder and genitalia
Parasympathetic Division Outflow
Oculomotor Nerve and Ciliary Ganglion
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings
Facial Nerve and Pterygopalatine Ganglion
• Greater petrosal nerve
•
+
Deep petrosal nerve
•
Nerve (Vidian) of pterygoid canal
• Pterygopalatine ganglion
• Postganglionic parasempathetics
• Lacrimal glands
• Nasalivary glands
• Salivary glands
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings
Facial Nerve and Submandibulare Ganglion
• Chorda tympani
• Joins to lingual nerve
• Reach to submandibular
ganglion via rami ganglionares
• Submandibular ganglion
• Postganglionic parasympathetics
• Subligual gland
• Submandibular gland
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings
Facial Nerve and Pterygopalatine & Submandibular
Ganglions
Greater petrosal nerve
Pterygopalatine
ganglion
Vidian
Lingual nerve
Sumandibular ganglion
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings
Deeper petrosal nerve
Superior
salivatory
nucleus
Chorda tympani
Facial Nerve and Pterygopalatine & Submandibular
Ganglions
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings
Glossopharyngeal Nerve and Otic Ganglion
• Parasympathetics of CN IX
• Lesser petrosal nerve
• Otic ganglion
• Postsinaptic parasempatetics join
to auriculotemporal nerve
• Parotid gland
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings
Glossopharyngeal Nerve and Otic Ganglion
Lesser petrosal nerve
Auriculotemporal nerve
n. petrosus profundus
Tympanic plexus
Tympanic nerve
Otic ganglion
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings
Autonom Nervous System-Summary
Autonom Nervous System-Summary
Autonom Nervous System
Autonom Nervous System
Autonom Nervous System